<template>
  <div class="todo-footer">
    <label>
      <input type="checkbox" v-model="allIsChecked"/>
    </label>
    <span> <span>已完成{{doneNum}}</span> / 全部{{ todoList.length }} </span>
    <button class="btn btn-danger" @click="deleteAllHandle">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  name: "Footer",
  props: ["todoList","checkAllHandle","deleteAllHandle"],
  computed: {
    doneNum() {
     return this.todoList.reduce((p, c) => (c.done ? p + 1 : p), 0);
    },
    allIsChecked:{
      get(){
        //全选的逻辑,当数组的每个元素的done都是true,则allIsChecked是true,其他都是false
       return this.todoList.every(item=>item.done)&&this.todoList.length!==0
      },
      set(e){
        //当计算属性的值改变时就会触发set函数(e,是checked的值true/false),把这个e传给app 在app中根据e的值修改todoList的值
        // console.log(e,'e');
        this.checkAllHandle(e)
      }
    }
  },
};
</script>

<style scoped>
/*footer*/
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}

.todo-footer label {
  display: inline-block;
  margin-right: 20px;
  cursor: pointer;
}

.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}

.todo-footer button {
  float: right;
  margin-top: 5px;
}
</style>